For anybody who really wants a satisfactory two-up seat on a Monster, I recommend the following steps.
1. Find somebody with a late 07-plus S4Rs or S4RT and check whether the seat fits your bike. These seats have an extra boss either side of the latchpin which adds support for the 'pillion' section. That extra support prevents the seat resting on the tail light housing when loaded with passenger.
Sorry, don't have an easy pic but the plastic bosses are moulded into the seat pan about the same place as the rearmost rubber bumpers on this Corbin design:
It is easy to distinguish this later model seat from the 06-and-earlier version.
2. Purchase said seat, either new or from a wreck.
3. Send said seat to an aftermarket seat builder for remodelling into a two-up version. Tell the builder it doesn't need to accommodate the rear cowl (because you won't be using the cowl when carrying a passenger).
4. Fit remodelled seat when riding two-up.
That is essentially the route I took. Works brilliantly. Seat is comfy for two over just about any distance.
Surprisingly, still looks very good.
I had the builder also remodel the front for more comfort, plus add about 15mm height front and rear. The extra height makes a dramatic difference to leg comfort for the rider, no more cramping for me (182cm tall).
Downside: cost.
Sorry, no pics available but if anybody was desperate to see the result I could take a couple and post.
Other option of course would be to have Corbin build a custom seat for you along the same lines. Their stock model is constrained by trying to preserve ability to fit the rear cowl - not really necessary since seats are so easy to swap on the Monster - and for some reason they make the rider's section lower when for many of us it needs to be higher.
I hope it is okay embedding Corbin's pic in this post - I figure it is a free ad for them.
Edit: Perhaps worth noting that these late model seats - and the Corbin above - were not compatible with the Ventura rear bag system I had at the time, and AFAIK that's not changed.
